1. Field of the Invention
This invention relates to methods and apparatus for protecting a wire line and more specifically to a tube and bushing arrangement for protecting a wire line near the top of a well while fluid is being pumped into the well about the wire line.
2. Related Art
In situations such as fracturing in oil wells for secondary production of oil, fluid is pumped into a well at high pressure and flow rate. Flow is indicated by the arrows 10 in FIG. 1. A wire line 12 having a tool 14 attached to the end may be passed into the well at a point near the wellhead 16 for performing operations in the well. The wire line may pass into the well from outside through a rigid pipe 18. The pipe protects the wire line at the point where the wire line enters the flow passage 20.
The rigid pipe may typically be several feet long over that portion of the pipe which is inside the flow passage. Though the rigid pipe protects that portion of the wire line interior to the pipe, there is still a substantial amount of turbulence in the fluid flowing past the pipe and wire line. Since the pipe is rigid and the wire line is relatively flexible compared to the pipe, it is believed that the fluid flow past the pipe and wire line causes that portion of the wire line external to the pipe to whip back and forth with respect to the pipe. This causes wear on the wire line and ultimately severance of the wire line at the point 22 where the wire line exits the pipe.